Transcript A Time Projection Chamber for the next high energy e e

Linear Collider TPC R&D in Canada
Madhu Dixit
Carleton University
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
ExB & track angle systematics in a TPC
(Aleph TPC example)
TPC wire/pad readout
100 µm
•Average Aleph resolution ~ 150 µm
•About 100 µm best for all drift distances
• Limit from diffusion  (10 cm drift) ~ 15 µm;  (2 m drift) ~ 60 µm
•100 µm limit for all drift distances comes from wide pad response
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
TPC read out with a Gas Electron Multiplier
(GEM*)
* F. Sauli, NIM A386,531 (1997)
•GEM spatial resolution ~ 40 µm
with 200 µm pitch anodes
•Impractical for a TPC
•TPC pad widths ~ mm
•All charge on a single pad for a
TPC in high B field
•Difficult centroid finding
•Resolution ~ Pad width/√12
How to find charge centroid in a GEM?
– Zigzag shape makes chevrons share charge between pads to
facilitate centroid finding
– Optimize readout geometry and diffusion to do the best with
rectangular pads
– Where is the induced signal on the neighboring pads?
Stanford 25/9/2003
M. Dixit
MPGD-TPC R&D in Canada - Goals
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New ideas to get good space-point resolution from ~ mm wide pads
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Limits to achievable resolution by with conventional techniques by
optimizing geometry and gas diffusion
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Studies with a GEM & Micromegas test cells using collimated x-rays
15 cm drift TPC with GEM readout
Operating parameters
Cosmic ray tracking studies
Assess the performance of MPGD-TPC in a test beam and in a high
magnetic field
(r-) ~ 70 µm within reach with R&D,
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Pads centroid from induced signals in a GEM
GEM
Anode pads
Proportional wire
Cathode pads
• Short ~ 200 ns signal
•Wire/pad readout electronics
won’t work!
•Need fast high frequency pulse
shape sampling electronics
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Resistive anode GEM test cell setup
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Stanford 25/9/2003
M. Dixit
Outlook & summary
• Consensus for a 500 GeV e+ e- linear collider
within this decade - proposals in Europe & in the
US & Japan
• A micro-pattern detector (MPGD) readout TPC is
being be developed for the LC detector with
resolution and 2 track resolving power approaching
diffusion limits
• Better MPGD-TPC resolution has a significant
impact on the design of the LC detector design and
its physics reach
Stanford 25/9/2003
M. Dixit